The Internet has the potential to increase the capacity and accessibility of mental health services. This study aimed to investigate whether an unguided Internet-based self-help intervention delivered without human support or guidance can reduce symptoms of depression in young people at risk of depression. The study also aimed to explore the usage of such sites in a real-life setting, to estimate the effects of the intervention for those who received a meaningful intervention dose and to evaluate user satisfaction. Young adults were recruited by means of a screening survey sent to all students at the University of Tromsø. Of those responding to the survey, 163 students (mean age 28.2 years) with elevated psychological distress were recruited to the trial and randomized to an Internet intervention condition or the waiting list control group. The Internet condition comprised a depression information website and a self-help Web application delivering automated cognitive behavioural therapy. The participants in the waiting list condition were free to access formal or informal help as usual. Two-thirds of the users who completed the trial initially reported an unmet need for help. The findings demonstrated that an unguided intervention was effective in reducing symptoms of depression and negative thoughts and in increasing depression literacy in young adults. Significant improvements were found at 2-month follow up. Internet-based interventions can be effective without tracking and thus constitute a minimal cost intervention for reaching a large number of people. User satisfaction among participants was high.